• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.58-61
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• 2006

The effect of the steel ratio on the behavior of continuously reinforced concrete pavement (CRCP) under moving wheel loads and environmental loads were investigated in this study. The CRCP sections having different steel ratios of 0.6, 0.7, and 0.8% were considered: (1) to evaluate the load transfer efficiency (LTE) at transverse cracks; (2) to investigate strains in CRCP when the system is subjected to moving vehicle loads; (3) and to investigate the time histories of the crack spacing variations. The LTEs were obtained by conducting the falling weight deflectometer (FWD) tests. The strains in the concrete slab and the bond braker layer under moving vehicle loads were obtained using embedded strain gages. The results of this study show that the LTEs at transverse cracks are very high and not affected by the steel ratio. The strains in CRCP under vehicle loads become smaller as the vehicle speed increases or as the wandering distance increases; however, the strains are not clearly affected by the steel ratio. However, the changes in the crack spacings are affected by the steel ratio.

• 대한치과교정학회지
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• 제8권1호
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• pp.49-58
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• 1978

This investigation was undertaken to know how the bony facial profile could be changed with age. The 5 serial lateral cephalometric roentgenograms of the fourteen boys and fourteen girls between 7 and 11 years of age were studied and the findings seems to warrant the following conclusions. 1. The manaible tended to become more prognathic in relation to the cranial base (S-N) during growth, but the maxilla showed very little change. 2. There was increase in the inclination of the lower border of mandible associated with the increase in mandibular prognathism. 3. There was a tendency to being straight in bony facial profile due to the decrease in angle ANB with age. 4. The chin portion had a tendency to forward and downward growth in relation to the cranial base but there was slight strong tendency in downward growth. 5. The vertical growth was more prominant in the maxilla than in the mandible. 6. There was uniform and gradual increase of all measurements during growth. 7. Dimension of the craniofacial complex was larger in the boys than in the girls but this difference was not statistically significant. 8. Individual variation in skeletal growth was a normal occurrence.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.294-298
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• 2003

The complex, unsteady, self-sustained pressure oscillations induced by supersonic flow past a rectangular cavity is investigated using numerical simulations. The present numerical study is performed using a parallel, multiblock solver for the two-dimensional, compressible Navier­Stokes equations. Open cavities with length-to-depth (L / D) ratio in the range 0.5 - 3.3 are considered. This paper sheds light on the cavity physics, cavity oscillatory mechanism, and the organisation of vortical structures inside the cavity. The vortex shedding phenomenon, the shear layer impingement event at the aft wall and the movement of the acoustic/compression wave within the cavity are well predicted. The vortical structures· and the source of the acoustic disturbances are found to be located near the aft wall of the cavity. With the increase in the cavity length, strong recompression of the flow near the aft wall leading to a sudden jump in the cavity form drag is observed. The estimated cavity tones are in good agreement with the available semi­empirical relation. Multiple peaks are noticed in deep and long cavities. For the present free­stream Mach number 1.71, it is observed that around L/D=2.0, the cavity oscillatory mechanism changes from the transverse to longitudinal oscillatory mode. The effects of this transition on various fluid dynamics and acoustic properties are also discussed.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.95-98
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• 2005

This paper proposes the solutions predicting the coefficient of the thermal expansion changes of composites which include the fiber-like shaped ($a_1$ > ($a_2$ = ($a_3$) and the disk-like shaped (al = a2> a3) inclusions like two dimensional geometries, which has one aspect ratios, ${\alpha}$ = ($a_1$ /($a_3$). The analysis follows the procedure developed for elastic moduli by using the generalized approach of Eshelby’s equivalent tensor. The influences of the aspect ratios, on the effective coefficient of thermal expansion of composites containing aligned isotropic inclusions are examined. This model should be limited to analyze the composites with unidirectionally aligned inclusions and with complete binding to each other of both matrix and inclusions having homogeneous properties. The coefficient of thermal expansion of composites (${\theta}_{11}$,${\theta}_{22}$and ${\theta}_{33}$) are investigated. From material data of the composites with glass fiber in epoxy resin, the thermal expansions along the aspect ratio were obtained and similar to the Chow model. The longitudinal coefficients of thermal expansion ${\theta}_{11}$decrease, as the aspect ratios increase. However, the transverse coefficients of thermal expansion ${\theta}_{22}$increase or decrease, as the aspect ratios increase. And both of them decrease, as the concentration increases.

• 한국기계가공학회지
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• 제14권4호
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• pp.118-125
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• 2015

The roll-forming process is a highly productive incremental forming process and is suitable for manufacturing thin, high-strength steel products. Recently, this process has been considered one of the most productive processes in manufacturing high-strength steel automotive structural parts. However, it is very difficult to develop the roll-forming process when the cross-sectional shape of the product changes in the longitudinal direction. In this study, a roll-forming process for manufacturing high-strength steel automotive parts with a linearly variable symmetric hat-type cross-section was developed. The forming rolls were designed by the 3D CAD system, CATIA. Additionally, the designed forming rolls were modified by the simulation through the 3D elastic-plastic finite element analysis software, MARC. The results of the finite element analysis show that the final roll-forming roll can successfully produce the desired high-strength steel automotive part with a variable cross-section.

• 성인간호학회지
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• 제15권4호
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• pp.617-627
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• 2003

Purpose: The purpose of this study is to investigate fatigue and its related factors in cancer patients receiving radiotherapy. Method: The subjects of this study consisted of 98 patients receiving radiotherapy. Subjects were recruited from C University Hospital radiation oncology unit located in Gwangju from March to May, 2001. Questionnaire and medical records were used for data collection. The obtained data was analyzed using SAS program that included descriptive statistics, t-test, ANOVA, Post-hoc test(Fisher's LSD) and Pearson's correlation coefficients. Result: The fatigue perceived by the subjects was middle level ($5.59{\pm}1.59$) and 72.4% of them reported greater than 5 points. The subjects in no religion, low income, and spouse caregiver groups experienced the higher fatigue than another groups, respectively. The subjects in nasopharyngeal cancer, head & neck radiation site, and analgesics medication groups did, experience fatigue as well. The fatigue not only positively correlated with symptom distress, disruption of usual activity, sleep dissatisfaction, and mood state, but also negatively with less family support. Conclusion: Cancer patients receiving radiotherapy experience the middle level of fatigue and it correlates with the multi-dimensional factors. However, further research is needed to identify the changes in fatigue over the radiotherapy period through longitudinal design and to develop nursing intervention for fatigue decrease.

• 음성과학
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• 제15권2호
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• pp.33-51
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• 2008

Difference of learner speech and loanword phonology is investigated in terms of Korean learners' speech and their loanword adaptation of English words with a post-vocalic word-final stop. When we compared the speech of 12 Korean learners in mid-intermediate level with that of eight English speakers, the learner speech did not reflect loanword phonology of the vowel insertion after a voiced word-final stop (e.g., rib$[\dotplus]$, bad$[\dotplus]$, gag$[\dotplus]$ vs. tip[=], cat[=], book[=]), but, instead, the target phonology of vowel lengthening before a voiced word-final stop (e.g., rib[r.I:b], CAD$[k{\ae}:d]$, bag$[b{\ae}:g]$ vs. rip[rI.p], cat$[k{\ae}t]$, back$[b{\ae}k])$. A longitudinal study of learner speech before and after instruction showed some development toward the acquisition of target phonology. The results indicate that learner speech departs from loanword phonology, and approaches to target speech in a faster rate than direct ratio. Thus, native phonology predicts loanword phonology, but lends little support to learner speech. Our results also indicate that loanword phonology is constant, while learner speech changes toward the acquisition of target phonology.

• 한국안전학회지
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• 제31권1호
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• pp.139-147
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• 2016

Nuclear energy is considerably cheap and clean compared to other fossil fuels. Yet, there are rising safety concerns of nuclear power plants including the possibility of radiation releasing nuclear accidents. In light of the Fukushima nuclear crisis in 2011, Japan has been re-evaluating their existing energy policies and increasing the share of alternative energy. This paper first tracks the major historical changes of energy policy in Japan by time period. Next, energy security, reignited concerns and alternative energy are covered to examine Japan's energy security situation and its transition after the Fukushima disaster. Lastly, a short survey based on thematic analysis was conducted in South Korea and Japan to understand the public awareness of nuclear. This paper postulates that the case of Fukushima will contribute to establish and operate a safe-future nuclear program in South Korea, given that the country is not only geographically neighbouring Japan but also the world's fourth largest producer of nuclear energy.

• Journal of applied mathematics & informatics
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• 제35권3_4호
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• pp.241-260
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• 2017

An analysis is made to study the solute transport in a Casson fluid flow through an annulus in presence of oscillatory flow field and determine how this flow influence the solute dispersion along the annular region. Axial dispersion coefficient and the mean concentration expressions are calculated using the generalized dispersion model. Dispersion coefficient in oscillatory flow is found to be a function of frequency parameter, Schmidt number, and the pressure fluctuation component besides its dependency on yield stress of the fluid, annular gap and time in the case of steady flow. Due to the oscillatory nature of the flow, the dispersion coefficient changes cyclically and the amplitude and magnitude of the dispersion increases initially with time and reaches a non - transient state after a certain critical time. This critical value varies with frequency parameter and independent of the other parameters. It is found that the presence of inner cylinder and increase in the size of the inner cylinder inhibits the dispersion process. This model may be used in understanding the dispersion phenomenon in cardiovascular flows and in particular in catheterized arteries.

• 대한기계학회논문집B
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• 제27권7호
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• pp.948-955
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• 2003

Pressure coefficient in rotating discharge hole was measured to gain insight into the influence of rotation to the discharge characteristics of rotating discharge hole. Pressure measurements were done by the telemetry system that had been developed by the authors. The telemetry system measures static pressure using piezoresistive pressure sensors. Pressure coefficients in rotating discharge hole were measured in longitudinal direction and circumferential direction with various rotating speed and 3 pressure ratios. From the results, the pressure coefficient, and therefore the discharge coefficient, is known to decrease with the increase of Ro number owing to the increase of flow approaching angle to the discharge hole inlet. However, there exists critical Ro number where the decrease rate of discharge coefficient with the increase of Ro number changes abruptly; flow separation occurs from the discharge hole exit at this critical Ro number. Critical Ro number increases with the increase of length-to-diameter ratio, but the increase is small where the length-to-diameter ratio is higher than 3. The decrease rate of discharge coefficient with the increase of Ro number depends on the pressure recovery at the discharge hole, and the rate is different from each length-to-diameter ratio; it has tendency that the short discharge hole shows higher decrease rate of discharge coefficient.